Expansion boring tool



. Il o l 2 5 6 E j 3 :uw 3 m f 2afw 1 M QV- l oo /l 1 F f /j un. |2|l| d Q i .W A y s ,0J Hmm j ...m1 1 8 MBK j 5mn .M 7 mm I Z 3 .u1u z L, 1l a O Patented Oct. 11, 1932 `UNITED -STrflfISv PATENToFFlcE 1I'AMIES E.v KILZER, OF ST. LOUIS, MISSOURI, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

DAVIS BORING TOOL COMPANY, OF ST. LOUIS, MISSOURI, A CORPORATION OF MIS- SOURI EXPANSION BORING TOOL `Application rled February 13,1928. Serial No. 253,874.

' This inventionpertains to boring tools of y the expansion type;

One of the objects of this invention is to provide aboring tool of simplified construc- "tion,'which will becheap to manufacture and at the same time capable of accurate adjustment.

Another object is to provide a construction which will operate with reduced wear on certain parts. Y

lAnother object is to provide improved Vmeans for moving the cutters for adjustment.

Another object` is to provide improved means for locking the cutters in adjusted po- A the accompanying drawing, in whichwedge block in use.

Figure 1 is a longitudinal section of a boring bar embodying this invention, taken on line 1 1 of Figure 2;

Figure 2 is a transverse section, taken on line 2-2 of Figure l;

Figure 3 is a perspective view of the wedge block;

Figure 4 is a view similar to Figure 3, showing the wedge block for use in inverted position; and

Figure 5 is a view similar to Figure 2, but on a reduced scale, showing the inverted Referring to the drawing, 1 designates the boring bar, which may be of any suitable design, and is provided with a trans-verse slot 2, in which the cutters 3 are adapted to move to adjustment. The transverse slot 2 is intersected at the center of the bar 1 by a transverse or radial cylindrical bore 4. Fitted to move longitudinally in the bore 4 is a wedge block or bushing 5.

The wedge block 5 is generally cylindrical in shape, as shown in Figures 3 and 4, but has a portion thereof cut away to provide a series respondingly beveled surfaces 7 on the rear Y of the cutters 3. The portion of the bushing 5 not cut away provides a pair of ns 8. These fins 8 yare adapted to fit snugly within guide slots 9 in the cutters 3. One of the fins '8 is provided with a slot 10 therealong adapted to receive the projecting end of one or more pins 11, which project into the bore 4 at aV suitable point to properiy 'position the wedge bloclrin the bore. rihe wedge block is provided with a thread 12 extending centrally therethrough.

An adjustingscrew 13 is provided with an enlarged head 14 having a flange 15 adapted to fit an annular seat` at the outer end of the bore 4, as shown in Figure 2. The other end of the screw 13 has a portion thereof reduced in diameter toprovide a ournal 16. The reduction of diameter provides a shoulder 17 j adjacent thisl journal. At the inner end of the bore 4 a socket 18 is provided to receive the ournal 1G`and to forni a bearing therefor. The head 14 is circular in form land is surroundedby a ring retainer 19, which is threaded intofthe boring bar 1 and provides an abutment for the iange 15.

In order to retain the cutters 3 in adjusted position, alocking pin 2O is provided for each cutter. The pins 2O are inserted into suitable sockets in the bar 1 adjacent the cutters 3 and running transversely thereof. The upper ends of these pins are provided wi h threaded portions 21 engaging a similar thread in the upper end of the socket. That portion 22 of the pin 2O which comes opposite the cutter 3 when the pin has been prop erly inserted is turned eccentric with and smaller than the body of the pin. The socle ets in which these pins are seated are positioned so as to intersect the slot 2 in such a waythat when the pin 20 is turned, the eccentric portion 22 will bind against the cutter to lock the same in position.

In the construction shown in Figure 2, the cutters are moved by turning the screw 13 right-handedly' in the usual manner to force the, cutters 3 outwardly to a greater-diameter. As it has been established as' a standard for boring tools of this type that the adjusting screw is turned right-handedly in order to eXp-and the cutters, this arrangement will require a left hand thread lon the screw 13. The retaining'ring 19 provides an abutment to take up the thrust of the screw during the expanding operation. This ring is securely held by beingthreaded into the boring bar. After being adjusted in place, this ring may be peened over at its edges so asto retain it securely in position.l

Itr Will be noted that in this device the adjusting'screvv 12? .is maintained accurately in its central position by bearingsat both ends thereof.'v 'This insures accuracy m the travel ofthe wedge block y5. The fins 8 also( act as guides in the slots 9 so as to guide the movement of the cutter, keeping the rear end central, in the Vslot 2 and avoidfbindingofthe same.

It will be noted that the wedge block may be used in either upright ory inverted position. In the position of Figure 5', the block is shown in` inverted position, and in this case it moves upwardly during expansion of the cutters. This construction requires a right-hand thread on the screw `13. It will be noted that the Vsamecutters Ymay befused with either of the constructions lof Figures 2 or .5," since the rear ends of the cutters must be beveled both Vways to make them interchangeable. In the construction of Figure 5, the lower end of the s crew has a thrust bearing at the shoulder 17 against the boringbar at the inner end of the bore a. In this figure the heavy'thrustcomes at this end andthe reduced extent ofthe thrust bearing at this end reduces the amount of wear at that point.

' It will be noted that bythreadingthe pins 20 into their sockets, provision is made both for securing them in their'sockets and for permitting rotation ofthe same in order to lock and unlock the cutters. In assembling the device, the pins 2O are first :screwedV into their proper position and then turnedso as to move the eccentric portion 22 away from the cutter, after which the cutter may be` inserted in its slot. This is necessary on account of the fact that the sockets for the pins 20 intersect the slot 2 and withA the cutters in place the fullsized ends ofthe pins could not be insertedfpast the cutters. y Y

It will be seen, therefore, that this invention provides a simple and rugged construction for an expansion boring tool. yThe number of partsv has been reduced to a minimum.

' All guides and bearings are in the boring bar itself, rather than in separate bearings or bushingsorthe like, all of which introduce inaccuracies into the .adjustment of the tool.

It is obvious that various changes may be made, within the scope of the appended .l j claims, in the details of construction withoutV .1 a cutter movable in said slot, a wedgeblock guided in said bore and having a guiding iin, said cutter having a slot adapted to receive said iin, and means for moving said block, Y

whereby to movesaid cutter.

2. An expansion boring tool, comprising,

f a boring bar having a transverse slot therein .and a transverse borejfintersecting said slot, a cutter movable 1n said slot and having a recess in its inner end, a wedge blockv hav- 'ing a "guidemember engaging the wallof;

said bore to lguide the blockand engaging said recess 'to guide said cutter, saidblock Valso having a wedge member engaging said cutter to move the same, and means for moving said block-along said bore.

3. An expansion boring tool, comprising, a boring bar having a transverseV slot therein and a transverse bore intersecting saidslot,

a cutter movable in said slot `and having a` recess in itsinner end, a wedge block having a guide' member engaging thewall of said boreito guide the block vand engaging said recess to guidel said cutter, said block also having V a wedge member engaging said cutter to 'move the same, means for moving Ysaid block along saidvbore, and a lockingpin threadedv into saidhar adjacent said cutter and undercut to form an eccentric portion adapted to lock saidy cutter. Y v

In testimony whereof I aiiix my signature this 10th day ofl Februarv, 1928.

JAMES, Y 

